compat.py now differentiates between Jython and CPython and chooses a
Jython-compatible lazyByteSlice for Jython.
twisted.internet.abstract: added a check for Jython that will avoid using
buffer() which does not exist - sharing the codepath with PY3.
threadable.getThreadID(): now works on Jython as well (added a check
in the form of a NameError exception).